Al(1-y-z)GayInzN (0≦y≦1, 0≦z≦1, and 0≦y+z≦1) crystals, such as aluminum nitride (AlN) crystals, having an energy bandgap of 6.2 eV, a thermal conductivity of approximately 3.3 WK−1 cm−1, and high electrical resistance have been used as materials for semiconductor devices, such as short-wavelength optical devices and power electronic devices. Conventionally, such crystals have been grown on a base substrate, for example, by a vapor phase epitaxy method.
Si(1-v-w-x)CwAlxNv substrates have received attention as base substrates on which such materials are grown. For example, U.S. Pat. No. 4,382,837 (Patent Literature 1), U.S. Pat. No. 6,086,672 (Patent Literature 2), and Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2005-506695 (Patent Literature 3) describe a method for manufacturing a Si(1-v-w-x)CwAlxNv substrate.
Patent Literature 1 discloses that a raw material is heated at a temperature in the range of 1900° C. to 2020° C. to grow (SiC)(1-x)(AlN)x crystals on Al2O3 (sapphire). Patent Literature 2 discloses that a raw material is heated at a temperature in the range of 1810° C. to 2492° C. to grow (SiC)(1-x)(AlN)x crystals on silicon carbide (SiC) at a temperature in the range of 1700° C. to 2488° C. Patent Literature 3 discloses that (SiC)(1-x)(AlN)x crystals are grown on silicon (Si) at a raw material gas temperature in the range of 550° C. to 750° C.